The NUP98-HOXD13 fusion gene implicated in human leukemia induces myeloproliferation and blocks early b cell development in murine hematopoiesis

Abstract

The nucleoporin gene NUP98 (11p15) has been reported to be fused to a number of genes including the homeobox HOX genes A9 and D13 in therapy-related AML. To investigate the role and effects that the fusion gene may have on hematopoiesis and in the development of leukemia, we used the MSCV retrovirus (GFP as a selectable marker) to express the NUP98-HOXD13 cDNA in murine bone marrow (BM). NUP98-HOXD13 (GFP+) transduced BM cells had a 1.8 fold increase (n = 5) in clonogenic colony forming cell numbers in vitro, compared to control GFP+ BM cells. Moreover, they yielded a 20 fold increase in day 12 CFU-S following 1 week in liquid culture. To assess the effect on hematopoiesis in vivo, mice were transplanted (TX) with transduced BM cells (n = 9). BM biopsy and peripheral blood analysis (PB) 12 weeks post-TX revealed a reduced level of circulating B220+ B cells (0.72 vs 2.47 × 106/ml) and a 25 fold reduction in B cell clonogenic progenitors in the BM. Two NUP98-HOXD13 mice sacrificed 18 weeks post-TX for further analysis manifested varying degrees of increased myelopoiesis. One mouse had clear signs of early myeloproliferative syndrome (MPS), including a marked increase in splenic CFC-GM (65 fold) and Gr-1+ cells (4 fold). The myeloproliferation was transplantable and progressive with 2 of 5 secondary mice becoming moribund by 10 weeks post-TX and MPS, as shown by increased PB counts, splenomegaly and myeloid cell infiltration in multiple organs. These results provide direct evidence of the potential of NUP98-HOXD13 to grossly perturb hematopoiesis.